Methanol production via dry reforming and methanol synthesis in a vessel

ABSTRACT

A system and method for producing methanol via dry reforming and methanol synthesis in the same vessel, including converting methane and carbon dioxide in the vessel into syngas including hydrogen and carbon monoxide via dry reforming in the vessel, cooling the syngas via a heat exchanger in the vessel, and synthesizing methanol from the syngas in the vessel.

TECHNICAL FIELD

This disclosure relates to dry reforming of methane and methanolsynthesis.

BACKGROUND

Methane may be labeled as the simplest hydrocarbon. Methane may besubjected to steam reforming to generate synthetic gas (syngas) thatincludes hydrogen (H₂) and carbon monoxide (CO). The syngas may bedistributed to different facilities as a feedstock for generatingchemicals or chemical intermediates. The hydrogen may be separated fromthe syngas to produce hydrogen.

Carbon dioxide is the primary greenhouse gas emitted through humanactivities. Carbon dioxide (CO₂) may be generated in various industrialand chemical plant facilities. At such facilities, the utilization ofCO₂ as a feedstock may reduce CO₂ emissions at the facility andtherefore decrease the CO₂ footprint of the facility. The conversion ofthe greenhouse gas CO₂ into value-added feedstocks or products may bebeneficial.

SUMMARY

An aspect relates to a method of producing methanol via dry reformingand methanol synthesis, the method including providing feed includingmethane and carbon dioxide to a vessel, converting methane and carbondioxide in the vessel into syngas including hydrogen and carbon monoxidevia dry reforming in the vessel, cooling the syngas via a heat exchangerin the vessel, synthesizing methanol from the syngas in the vessel, anddischarging effluent (including methanol) from the vessel.

Another aspect is a method of producing methanol, including converting(dry reforming) methane and carbon dioxide via a dry reforming catalystin a dry reforming section in a reactor vessel into syngas includinghydrogen and carbon monoxide, wherein the converting comprises dryreforming. The method includes flowing the syngas from the dry reformingsection through a heat exchange section in the reactor vessel to coolthe syngas with a cooling medium in the heat exchange section. Themethod includes flowing the syngas as cooled from the heat exchangesection to a methanol synthesis section in the reactor vessel. Themethod includes synthesizing methanol from the syngas via a methanolsynthesis catalyst in the methanol synthesis section.

Yet another aspect relates to a methanol production system including areactor vessel having a feed inlet to receive a feed including methaneand carbon dioxide. The reactor vessel includes a dry reforming sectionhaving a dry reforming catalyst in the reactor vessel to convert themethane and the carbon dioxide into syngas including hydrogen and carbonmonoxide. The reactor vessel includes a heat exchange section having aheat exchanger in the reactor vessel to receive the syngas from the dryreforming section and cool the syngas with a cooling medium. The reactorvessel includes a methanol synthesis section having a methanol synthesiscatalyst in the reactor vessel to synthesize methanol from the syngasand discharge an effluent including the methanol from the reactorvessel.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of a system that produces methanol.

FIG. 2 is a diagram of a system that produces methanol, and which may beanalogous to FIG. 1 .

FIG. 3 is a block flow diagram of a method of producing methanol via dryreforming and methanol synthesis in the same vessel

FIG. 4 is an Aspen Plus® simulation diagram.

DETAILED DESCRIPTION

Some aspects of the present disclosure are directed to dry reforming andmethanol synthesis in the same vessel to generate methanol. Overall, themethanol may be generated from methane and carbon dioxide in the vessel.Methane and carbon dioxide may be fed to the vessel, and the methanolgenerated in the vessel may discharge from the vessel.

The methanol generation may be via dry reforming of the methane in thevessel. In particular, the methanol may be synthesized in the vesselfrom the synthetic gas (syngas) generated by the dry reforming. Again,the dry reforming and the methanol synthesis may occur in the samevessel. Thus, methanol production can be by performing both dryreforming and methanol synthesis in the same vessel.

Dry reforming may be beneficial for consuming the two-greenhouse gasesmethane (CH₄) and carbon dioxide (CO₂). Dry reforming is a process thatmay react CH₄ with CO₂ to produce syngas with the aid of catalyst. Thesyngas may include hydrogen (H₂) and carbon monoxide (CO). The dryreforming reaction may be characterized as CH₄+CO₂→2H₂+2CO.

Embodiments of the present techniques include a reactor for methanolsynthesis via dry reforming, and in which both the dry reformingreaction and the methanol synthesis reaction occur in the same reactorvessel. In certain embodiments, the reactor (reactor vessel) may have atleast three sections including a dry reforming section, a heat exchangersection, and a methanol synthesis section. The reactor converts carbondioxide and methane into methanol in the vessel of the reactor.

Due to the mounting concerns about climate change, CCUS (carbon capture,utilization, and storage) is a focus of research and development aroundthe world. The utilization can include conversion. CO₂ conversiontechnologies have attracted attention at least because of difficultiesassociated with geological storage of CO₂. An aim of CO₂ conversion maybe to utilize concentrated CO₂ (e.g. from CO₂ capture) as a feedstock toproduce valuable chemicals via various conversion processes.

In implementations herein, dry reforming of CH₄ is a CO₂ conversiontechnology for mitigating CO₂ emissions. The dry reforming of methane(DRM) has relatively high CO₂ utilization ratio (e.g., molar ratioCH₄:CO₂=1:1) and thus may facilitate CO₂ reduction. The dry reforming ofCH₄ may also reduce emissions of CH₄, which like CO₂, is a greenhousegas.

Embodiments herein utilize CO₂ as feedstock via DRM to produce methanol.As presented herein in embodiments, the syngas produced from DRM isutilized directly in methanol production. Again, the syngas producedfrom DRM may be primarily H₂ and CO at a molar ratio of 1:1 based on theideal thermodynamic equilibrium.

FIG. 1 is a system 100 that produces methanol 102. The feed 104 includesCO₂ and CH₄. Advantageously, utilization of CO₂ as feed can reduce CO₂emissions (the CO₂ footprint) at a facility. In implementations, the CH₄may be fed in a methane-rich stream, such as natural gas. Utilization ofCH₄ as feed can reduce CH₄ emissions at a facility.

The system 100 includes a reactor 106. The system 100 includes adownstream system 108 that processes effluent 110 from the reactor 106to give the methanol 102 product. The reactor 106 may generally be acontinuous reactor. The system 100 may generally be a continuous system.

The reactor 106 includes a reactor vessel 112 having sections (zones orportions) for performing multiple respective unit operations. Inimplementations, the three sections (dry reforming, heat exchange, andDME synthesis) discussed below are all generally in the interior of thevessel 112 to the inside of the vessel 112 wall. The reactor vessel 112may be metal, such as stainless steel. The reactor vessel 112 may have avertical orientation as depicted, or may have a horizontal orientation.In implementations, the vessel 112 may have elliptical heads. Thereactor vessel 112 may have nozzles (e.g., flanged, threaded, etc.) atinlets and outlets for coupling to inlet supply conduits and outletdischarge conduits. The reactor vessel 112 may have vessel internals(e.g., plates, perforated plates, conduits, distributors, baffles, etc.)to provide for and accommodate the division or segregation of the vessel112 into multiple sections. The three sections (parts) discussed belowmight be structurally separate in the vessel via, for example, dividerplates or divider meshes. In operation, fluid flow occurs from onesection to another section. Divider plates, if employed, may have holes.Distributers may also be employed to facilitate and distribute flow offluid. These and other vessel internals may be, for example, a stainlesssteel, a Hastelloy®, or an Inconel®, and the like. The reactor 106 maybe considered a single reactor for performing multiple operations at thesame time, and may be labeled colloquially as a “single-step” reactor inperforming multiple unit operations or steps contemporaneously (orsimultaneously) in the same vessel 112.

In the illustrated embodiment, the reactor 106 is configured to performtwo different reactions of dry reforming and methanol synthesiscontemporaneously in two respective sections, as discussed below. Whilethe methanol synthesis within the vessel 112 may be in sequencedownstream of the dry reforming within the vessel 112, the two reactionsmay occur as the same time in the continuous operation of the reactor106.

The reactor 106 includes a dry reforming section 114 to perform (viareforming catalyst 116) the dry reforming reaction represented byCH₄+CO₂→2 H₂+2CO. The dry reforming section 114 may be labeled as a dryreforming zone, dry reforming part, dry reformer, etc. The dry reformingsection 114 may be enclosed within the reactor vessel 112 of the reactor106. The dry reforming section 114 has dry reforming catalyst 116 toconvert CH₄ and CO₂ of the feed 104 into synthetic gas (syngas) that isH₂ and CO. The dry reforming catalyst 116 may be a fixed bed of catalystin the dry reforming section 114. In certain implementations, the dryreforming catalyst 116 is a nickel-based catalyst. The dry reforming canbe conducted, for example, at less than 850° C., less than 800° C., inthe range of 700° C. to 900° C., in the range of 750° C. to 875° C., orin the range of 800° C. to 850° C. The molar ratio of the CO₂ and CH₄ inthe feed 104 to the dry reforming section 114 can vary, for example, inthe range of 1:1 to 3:1. As can be seen from the above dry-reformingreaction equation, the molar ratio of H₂ to CO in the generated syngasis 1:1 based on the ideal thermodynamic equilibrium, but in practice canbe different from 1:1. The molar ratio of H2 to CO in the producedsyngas is ideally 1 but in implemented production can be, for example,in the range of 0.4 to 1.

Moreover, as the dry reforming reaction is generally endothermic, heatmay be added to the dry reforming section 114. For instance, electricalheaters may be associated with the dry reforming section 114, or thereactor vessel 112 may have a vessel jacket at the dry reforming section114 for a heat transfer fluid (as a heating medium).

The reactor 106 includes a heat exchange section 118 that may be labeledas a heat exchange zone, heat exchange part, heat exchanger zone, heatexchanger portion, heat exchanger, etc. The heat exchanger is generallydisposed within the vessel 112. The heat exchange section 118 may beenclosed within the reactor vessel 112 of the reactor 106. A purpose ofthe heat exchange section 118 may be to cool the syngas 120 to a desiredtemperature for feed to the methanol synthesis.

In operation, the heat exchange section 118 cools the syngas 120discharged from the dry reforming section 114. In some implementations,the syngas 120 can include additional H₂ added to increase the molarratio of H₂ to CO in the syngas 120. The heat exchange section 116utilizes a cooling medium to cool the syngas 120. The cooling medium maybe, for example, water such as cooling tower water. The cooling mediummay flow through the heat exchange section 116 without change incomposition and absorb heat from the syngas 120.

In operation, the cooling medium supply 124 enters the heat exchangesection 118. The reactor vessel 112 may have a cooling-medium inlet(e.g., inlet nozzle) coupled to a supply conduit (external to the vessel112) conveying the cooling medium supply 124 to the reactor vessel 112.The cooling medium return 126 discharges from the heat exchange section118. The reactor vessel 112 may discharge the cooling medium return 126through cooling-medium outlet (e.g., outlet nozzle of the vessel 112)into a return conduit coupled to the cooling-medium outlet. The returnconduit 112 is general external to the vessel 112 and conveys thecooling medium return 126 to the cooling medium system.

With the cooling medium cooling (absorbing heat from) the syngas 120 inthe heat exchange section 118, the cooling medium return 126 has agreater temperature than the cooling medium supply 124. Heat transferoccurs from the syngas 120 to the cooling medium in the heat exchangesection 118. The cooling medium supply 124 may be, for example, lessthan 25° C. The cooling medium return 126 may be, for example, at least100° C.

The heat exchange section 118 may be, for example, a shell-and-tubeheat-exchanger type or configuration in which tubes are situated in theheat exchange section 118. The heat exchange section 118 can beconfigured to flow the cooling medium through the tubes, and flow thesyngas 120 external to the tubes. On the other hand, the heat exchangesection 118 can be configured to flow the syngas 120 through the tubes,and flow the cooling medium external to the tubes. Other heat exchangeor heat exchanger configurations are applicable.

The reactor 106 includes a methanol synthesis section 128 that may belabeled as a methanol synthesis zone, methanol synthesis portion,methanol synthesis reactor, methanol reactor, etc. The methanolsynthesis section 128 may be enclosed within the reactor vessel 112 ofthe reactor 106. The methanol synthesis section 128 receives the cooledsyngas 120 discharged from the heat exchange section 118. The methanolsynthesis section 128 has a methanol synthesis catalyst 130 to convertthe syngas 120 to methanol (e.g., methanol 102).

The methanol synthesis catalyst 130 may be, for example, a copper-basedcatalyst, copper oxide (CuO) based catalyst, or a zinc oxide (ZnO) basedcatalyst. The catalyst 130 may include copper (Cu), CuO, ZnO, aluminumoxide (Al₂O₃) (alumina), or magnesia, or mixtures thereof. In certainimplementations, the catalyst 130 includes a mixture of CuO and ZnO,supported on alumina. The catalyst 130 may be Cu—ZnO—Al₂O₃, sometimesmodified with ingredients contributing to the increase of the copperdispersion and stability. Other catalysts are applicable. The reactorvessel 112 may have the catalyst 130 in a fixed bed. In implementations,the reactor 106 may be characterized as fixed-bed reactor with respectto both methanol synthesis and dry reforming.

Catalytic conversion of H₂ and CO into methanol can be in the gas phase.The methanol synthesis section 128 may react the CO and H₂ from thesyngas 120, such as via flow over and/or through the bed of catalyst130, to produce methanol (CH₃OH). This methanol synthesis with respectto the CO can be characterized as a CO hydrogenation reaction:2H₂+CO→CH₃OH. Thus, a molar ratio of H₂ to CO of at least about 2 in thesyngas 120 stream received at the methanol synthesis section 128 may bedesirable. As appreciated by one of ordinary skill in the art, methanolsynthesis can be favored over DME synthesis. Embodiments can limit DMEsynthesis and favor methanol synthesis. For instance, methanol synthesismay be favored over DME synthesis by selection of the catalyst 130.Certain catalyst and its component ratios can provide better selectivityfor methanol production. For methanol synthesis, Cu-based catalyst maybe employed. In contrast, for the DME synthesis, Cu-based catalystcombined with acid catalysts such as γ-Al₂O₃, zeolites, orsilica-modified alumina, may be utilized.

Methanol can be produced by the hydrogenation of CO or CO₂ via thecatalyst 130. The methanol synthesis can be labeled as hydrogenation ofcarbon oxides (COX) to methanol. The carbon oxides (COX) are CO and CO₂.The operation may add hydrogen 122 (see discussion later) to increasethe molar ratio of H₂ to CO in the syngas 120 stream by up to 3 or moreto account for implementations in which CO₂ enters with the syngas 120flow. In implementations, the molar ratio of H₂ to CO being larger than2 in the entering syngas 12 stream may advance conversion of any CO₂that may enters in the syngas 120 stream in the methanol synthesisreaction and facilitate to suppress side reactions in the methanolsynthesis.

The methanol synthesis can be conducted, for example, at a temperaturein the range of 175° C. to 325° C. or in the range of 200° C. to 300°C., or at a temperature of at least 175° C., at least 200° C., or lessthan 350° C. The operating pressure can be, for example, in the range of10 bars to 70 bars or in the range of 10 bars to 50 bars. The unit baras used herein is bar absolute (bara). The H₂:CO feed molar ratio (e.g.,in the incoming syngas 120 stream) for methanol synthesis can be variedin the range, for example, of 1:1 to 3:1 or in the range of 1:1 to3.5:1. In some instances, to optimize (increase) the feed H₂/CO molarratio, extra H₂ (e.g., hydrogen 122) produced by water (H₂O)electrolysis utilizing renewable power sources can be injected into thereactor vessel 112.

In general, the residence time in the dry reforming section 114 (dryreforming reaction) and in the methanol synthesis section 128 (methanolsynthesis reaction) may be similar. However, the residence time in themethanol synthesis section 128 may be adjusted, for example, byinjecting hydrogen after the dry reforming section 114, by changing thecatalyst 130 volume (amount), and the like.

The methanol 102 synthesized may discharge from the methanol synthesissection 128 in effluent 110 from the reactor vessel 112. In someimplementations, an online analytical instrument 131 (e.g., an onlinegas chromatograph instrument) may be disposed along the dischargeconduit from the reactor vessel 112 to measure composition of theeffluent 110. In some implementations, the control system 148 inresponse to the effluent 110 composition as measured by the onlineanalytical instrument 131, may automatically adjust: (1) flow rate ofthe carbon dioxide 132 stream (see discussion later), (2) flow rate ofthe hydrogen 122, or (3) other operating conditions of the reactor 106.

In some implementations, the reactor vessel 112 may include a dischargeportion 133 to facilitate discharge of the effluent 110 of the reactor106. In other implementations, there is no independent discharge portion133. Instead, the reactor 106 may discharge the effluent 110 of thereactor 106 generally directly from the methanol synthesis section 128.

The methanol synthesis reaction in the methanol synthesis section 128that converts the syngas 120 to methanol 102 is typically exothermic.Therefore, the reactor vessel 112 at the methanol synthesis section 128may have a vessel jacket for a heat-transfer fluid that is a coolingmedium (e.g., cooling water). The reactor vessel 112 may have coolingcoils (internally in the reactor vessel 112 at the methanol synthesissection 128) that route a cooling medium. To cool the reaction mixtureand control temperature of the methanol synthesis section 128, heattransfer may occur from the reaction mixture in the methanol synthesissection 128 to the cooling medium in the reactor vessel jacket or in thecooling coils.

In the illustrated embodiment, carbon dioxide 132 is added to methane134 to give the feed 104 for introduction to the reactor vessel 112. Thecarbon dioxide 132 stream may be, for example, at least 90 percent (%)of CO₂ by volume (vol %) or on a molar basis (mol %). The methane 134stream may be a methane-rich stream (e.g., at least 60 vol % CH₄), suchas natural gas, or a process stream or waste stream having CH₄. The flowrate of the carbon dioxide 132 stream and/or the methane 134 stream maybe controlled to give a desired or specified percent concentration(e.g., vol % or mol %) of CO₂ in the feed 104 or a specified molar ratioof CO₂ to CH₄ in the feed 104. For example, the molar ratio of CO₂ toCH₄ in the feed 104 may be specified in the range of 1:1 to 3:1. Inimplementations, the amount of CO₂ in the feed 104 is in the range of 30vol % to 70 vol %, or at least 40 vol %. In the illustratedimplementation, the system 100 includes a control valve 136 (e.g., flowcontrol valve) to control (including adjusting) the flow rate of thecarbon dioxide 132 stream to give the specified percent (e.g., at least40 vol %) of CO₂ in the feed 104 or the specified molar ratio (e.g., atleast 1) of CO₂ to CH₄ in the feed 104. In implementations, the volumepercent or molar percent of each of CO₂ and CH₄ in the feed 104 can becalculated based on the known flow rates and compositions of the carbondioxide 132 steam and methane 134 stream. In one embodiment, an onlineanalyzer instrument 138 (e.g., online gas chromatograph instrument)disposed along the conduit conveying the feed 104 measures the amounts(e.g., in vol %) of each of CO₂ and CH₄ in the feed 104.

In some implementations, the control system 148 may automatically adjustthe set point of the control valve 136 in response to the composition ofthe feed 104 as calculated by the control system 148 or as measured bythe online analyzer instrument 138. A human operator or user may enterinto the control system 148 a specified value (a set point of a mastercontroller) related to the amount of CO₂ in the feed 104, such as forthe specified concentration of CO₂ in the feed or for the specifiedmolar ratio of CO₂ to CH₄ in the feed 104. To maintain this entered setpoint (of the master controller), the master controller may direct theflow controller (FC) of the flow control valve 136 as a slavecontroller. In particular, the master controller may specify a slave setpoint (e.g., volume flow rate of CO₂ 132 stream or mass flow rate of CO₂132 stream) of the FC for the control valve 136 to give the desired setpoint of the master controller.

The feed 104 may be introduced to an inlet portion 140 of the reactorvessel 112 to facilitate introduction of the feed 104 into the dryreforming section 114. In other implementations, the feed 104 thereactor vessel 112 does not include an independent inlet portion 140,and the feed 104 is instead introduced generally directly into the dryreforming section 114. In some embodiments, the carbon dioxide 132 andmethane 134 may be added in two respective separate streams to thereactor vessel 112 via two respective inlets of the reactor vessel 112.

In implementations, as mentioned, the molar ratio of H₂ to CO in thesyngas 120 as generated by the dry reforming section 114 may generallybe approximated at the molar ratio of 1 for the ideal thermodynamicequilibrium or stoichiometric relationship for the dry reformingreaction in the dry reforming section 114. In practice, however, themolar ratio of H₂ to CO in the syngas 120 as generated by the dryreforming section 114 may be, for example, in the range of 0.4:1 to 1:1.In implementations, the molar ratio of H₂ to CO in the syngas 120 may beestimated based on, for example, the relative amounts of CO₂ and CH₄ inthe feed 104, the operating conditions (e.g., pressure, temperature,etc.) of the dry reforming section 114, the condition of the dryreforming catalyst 116, and so forth. Again, in certain embodiments, themolar ratio of H₂ to CO in the syngas 120 as generated by the dryreforming section 114 is in the range of 0.4 to 1. The hydrogen 122(hydrogen gas H₂) may be added to increase this molar ratio to greaterthan 1, such as in the ranges of 1 to 2, 1.1 to 2, 1 to 3, or 1 to 4, orat a value of least 1.1, at least 1.2, at least 1.8, at least 2, or atleast 3. In certain implementations, an online analytical instrument(e.g., online gas chromatograph instrument) is disposed along thereactor vessel 112 to sample the syngas 120 (e.g., as cooled in the heatexchange section 118) to measure the composition of the syngas 120 (withor without the addition of the hydrogen 122) to give a measured value ofthe molar ratio of H₂ to CO in the syngas 120.

A source 142 of hydrogen provides the hydrogen 122 that is added to thereactor vessel 112 to increase the molar ratio of H₂ to CO in the syngas120. The methanol synthesis in the methanol synthesis section 128 maybenefit, for example, with the syngas 120 having a molar ratio of H₂ toCO of at least 1, at least 1.1, or at least 2. The hydrogen 122 may beinjected not only to adjust the molar ratio of the H₂/CO, but also toreduce the temperature of the syngas 120. The injected hydrogen 122 maybeneficially cool the syngas 120.

In implementations, the flow rate of the hydrogen 122 may be controlled(including adjusted) by a control valve 142 (e.g., flow control valve)to give the desired or specified molar ratio of H₂ to CO in the syngas120. In the illustrated embodiment, the addition point of the hydrogen122 is depicted at the discharge portion of the dry reforming section114. However, the hydrogen 122 may also be added to the heat exchangesection 118 or at the introduction of the syngas 120 (as cooled in theheat exchange section 118) to the methanol synthesis section 128.

In certain implementations, the source 142 of hydrogen 122 is a waterelectrolysis unit. Electrolysis of water is the decomposition of waterinto oxygen and hydrogen gas due to the passage of an electric current.The water electrolysis unit may include at least one water-electrolysiselectrochemical cell (electrolytic cell) having a pair of electrodesimmersed in water. An electrolyte (e.g., sulfuric acid, potassiumhydroxide, sodium hydroxide, etc.) may be added to the water. The pairof electrodes are a cathode and an anode. The cathode and anode may eachbe an inert metal, such as platinum, stainless steel, iridium, etc. Inoperation, an electric current may be provided to the cathode. Theelectrolysis of water may receive energy to overcome activationbarriers. In implementations, energy for the electrolysis of water inthe water electrolysis unit may be provided via renewable sources, suchas energy sources relying on wind or solar.

In the electrochemical cell of the water electrolysis unit, reduction ofthe water at the cathode generates H₂. Oxidation of water at the anodegenerates oxygen gas (O₂). The H₂ and 02 may be collected separately.The overall equation of the decomposition of the water in theelectrolytic cell can be: 2 H₂O→2 H₂+O₂. Therefore, the number ofhydrogen molecules generated may be twice the number of oxygen moleculesgenerated. The electrolysis of water via the water electrolysis unit mayproduce H₂ and O₂ at a H₂/O₂ molar ratio of 2 to 1. The number ofelectrons through the water can be at least twice the number ofgenerated hydrogen molecules and four times the number of generatedoxygen molecules.

As indicated, hydrogen 122 produced from the water electrolysis unit canbe added to the syngas 120 to adjust the molar ratio of H₂ to CO in thesyngas 120. As mentioned for some implementations, a flow control valve142 disposed along the conduit conveying the hydrogen 122 modulates theamount of hydrogen 122 added to give the desired or specified molarratio of H₂ to CO in the syngas 120. Again, the desired molar ratio maybe specified based on the desired molar ratio of H₂ to CO for themethanol synthesis. The addition of the hydrogen 122 may increase theH2:CO molar ratio, for example, to between 1 to 2, to between 1 to 3, orto between 1.5 to 3.5.

If needed, a hydrogen mechanical compressor can be disposed along theconduit conveying the hydrogen 122. The hydrogen compressor can providemotive force for flow (addition) of the hydrogen 122 into the reactorvessel 112.

In some implementations, the control system 148 may automatically adjustthe set point of the control valve 142 in response to the composition ofthe syngas 120 as calculated by the control system 148 or as measured byan online analyzer instrument. A human operator or user may enter intothe control system 148 a specified value (a set point of a mastercontroller) for the molar ratio of H₂ to CO in the syngas 120. Tomaintain this entered set point (of the master controller), the mastercontroller may direct the flow controller (FC) of the flow control valve142 as a slave controller. In particular, the master controller mayspecify a slave set point (e.g., volume flow rate of hydrogen 122 ormass flow rate of hydrogen 122) of the FC for the control valve 142 togive the desired set point of the master controller.

The effluent 110 discharged from the reactor 106 includes the methanol102 generated in the methanol synthesis section 128. In addition to themethanol 102, the effluent 110 may include H₂, CO, and CO₂. The amount,e.g., mole percent (mol %), of CO₂ in the effluent 110 may becorrelative with (e.g., directly proportional with) the amount of CO₂ inthe feed 104, or correlative with (e.g., directly proportional with)with the molar ratio or volume ratio of CO₂ to CH₄ in the feed 104. Inimplementations, the effluent 110 can include unreacted CH₄, such aswhen the conversion of the CH₄ of the feed 104 less than 100% in thereactor 106 (including in the dry reforming section 114). In certainimplementations, the effluent 110 includes less than 5 mol % of CH₄,less than 1 mol % of CH₄, less than 0.5 mol % CH₄, or less than 0.1 mol% of CH₄.

As mentioned, the effluent 110 of the reactor 106 may discharge from thereactor vessel 112 to a downstream system 108 for processing theeffluent 110. The downstream system 108 may be a separation system toremove components 144 from the effluent 110 to give the product methanol102. The components 144 may include, for example, H₂, CO, CO₂, H₂O, andany unreacted CH₄. Water can be produced by reverse water gas shiftreaction in the methanol synthesis section including under higherCO₂-amount dry-reforming condition. The components 144 may be recycledto the reactor 106 or sent to other users.

To separate the components 144 from the effluent 110, the downstreamsystem 106, e.g., separation system(s), may include membrane separatorvessel(s), distillation column(s), stripper column(s) having packing ortrays, or vessel(s) having adsorbent (that adsorbs and can beregenerated), or any combinations thereof. Various configurations areapplicable. The separation of the components 144 from the effluent 110in the downstream system 108 may involve multi-stage cooling (includingpartial condensation). The cooling and partial condensation may utilizeheat exchanger(s)), refrigeration compressor(s), and the like. Themulti-stage cooling may involve separation, such as via flash separationvessels, and the like.

The system 100 for producing methanol may include a control system 148that may facilitate or direct operation of the system 100, such as inthe operation of equipment and the supply or discharge of flow streams(including flow rate and pressure) and associated control valves. Thecontrol system 148 may receive data from sensors (e.g., temperature,pressure, etc.) and online analytical instruments in the system 100. Thecontrol system 148 may perform calculations. The control system 148 mayspecify set points for control devices in the system 100. The controlsystem 148 may be disposed in the field or remotely in a control room.The control system 148 may include control modules and apparatusesdistributed in the field.

The control system 148 may include a processor 150 and memory 152storing code (e.g., logic, instructions, etc.) executed by the processor150 to perform calculations and direct operations of the system 100. Thecontrol system 148 may be or include one or more controllers. Theprocessor 150 (hardware processor) may be one or more processors andeach processor may have one or more cores. The hardware processor(s) mayinclude a microprocessor, a central processing unit (CPU), a graphicprocessing unit (GPU), a controller card, circuit board, or othercircuitry. The memory 152 may include volatile memory (e.g., cache andrandom access memory), nonvolatile memory (e.g., hard drive, solid-statedrive, and read-only memory), and firmware. The control system 148 mayinclude a desktop computer, laptop computer, computer server,programmable logic controller (PLC), distributed computing system (DSC),controllers, actuators, or control cards.

The control system 148 may receive user input that specifies the setpoints of control devices or other control components in the system 100.The control system 148 typically includes a user interface for a humanto enter set points and other targets or constraints to the controlsystem 148. In some implementations, the control system 148 maycalculate or otherwise determine set points of control devices. Thecontrol system 148 may be communicatively coupled to a remote computingsystem that performs calculations and provides direction includingvalues for set points. In operation, the control system 148 mayfacilitate processes of the system 100 including to direct operation ofthe reactor 106 and the downstream system 108. Again, the control system148 may receive user input or computer input that specifies the setpoints of control components in the system 100. The control system 148may determine, calculate, and specify the set point of control devices.The determination can be based at least in part on the operatingconditions of the system 100 including feedback information from sensorsand instrument transmitters, and the like.

Some implementations may include a control room that can be a center ofactivity, facilitating monitoring and control of the process orfacility. The control room may contain a human machine interface (HMI),which is a computer, for example, that runs specialized software toprovide a user-interface for the control system. The HMI may vary byvendor and present the user with a graphical version of the remoteprocess. There may be multiple HMI consoles or workstations, withvarying degrees of access to data. The control system 148 can be acomponent of the control system based in the control room. The controlsystem 148 may also or instead employ local control (e.g., distributedcontrollers, local control panels, etc.) distributed in the system 100.The control system 148 can include a control panel or control moduledisposed in the field.

FIG. 2 is a system 200 that produces methanol 102. The system 200includes a reactor 206 that performs dry reforming of CH₄. The feed 104to the reactor 206 includes CO₂ and CH₄. The dry reforming of CH₄ withCO₂ as the oxidant is a technique that beneficially converts thegreenhouse-gases CO₂ and CH₄ into syngas that is primarily H₂ and CO.The molar ratio H₂ to CO in the syngas may deviate from idealthermodynamic equilibrium of 1 to in the range of 0.4 to 1, for example.Hydrogen may be added to the syngas in the reactor 206 to increase themolar ratio of H₂ to CO if desired.

The reactor 206 may be analogous to the reactor 106 of FIG. 1 . Thereactor 206 may include two reactors in the same reactor vessel: areactor for dry reforming CH₄ to generate syngas and a reactor formethanol synthesis from the syngas.

The reactor 206 is a vessel having at least three parts or sections(zones): dry reformer 208, heat exchanger 210, and methanol synthesisreactor 212, which are in the same vessel and analogous to the dryreforming section 114, heat exchange section 118, and methanol synthesissection 128 of FIG. 1 , respectively. The dry reformer 208 reactor andthe methanol synthesis reactor 212 are in the same reactor vessel. Inthe illustrated implementation, the heat exchanger 210 is also disposedin the same reactor vessel between the dry reformer 208 reactor and themethanol synthesis reactor 212.

The feedstock for the dry reforming may generally include CH₄ (ornatural that is primarily CH₄) and CO₂. The dry reforming may be atechnique for conversion of CH₄ and CO₂ into syngas without theintroduction of steam (water). Implementations are performed withoutintroduction of oxygen. Thus, embodiments of the dry reforming are notsteam reforming, not mixed-steam CO₂ reforming (MSCR) (which may also beknown as bi-reforming), and not autothermal reforming (ATR).

The feed 104 to the reactor 206 includes CO₂ and CH₄. Natural gas may befed to provide the CH₄. Natural gas includes primarily CH₄, for example,at 70-90 mol %. Natural gas may include higher alkanes (e.g., ethane,propane, butane) and other components (e.g., nitrogen, hydrogen sulfide,etc.) at a combined concentration, for example, less than 30 mol %. Incertain embodiments, the natural gas includes at least 80 mol % CH₄ orat least 90 mol % CH₄. The natural gas may be combined with a CO₂ streamhaving primarily CO₂ to give the feed 104. In embodiments, the naturalgas may have no measurable O₂ and/or measurable water (H₂O), or havetrace amounts of O₂ and/or H₂O. Natural gas generally has no more than 1mol % of O₂ and no more than 1 mol % of H₂O. If natural gas is fed, thenatural gas and the CO₂ of the feed 104 may be fed in a combined streamor as separate streams to the dry reformer 208 of the reactor 206. Theflow rate (e.g., volumetric rate, mass rate, or molar rate) of the feed104 may be controlled via at least one flow control valve (disposedalong a supply conduit) or by a mechanical compressor, or a combinationthereof. The ratio (e.g., molar, volumetric, or mass ratio) in the feed104 of the natural gas (or the CH₄ in the natural gas) to the CO₂ may beadjusted by modulating (e.g., via one or more control valves) at leastone of the flow rates of the natural gas or CO₂ streams. The supplypressure of the feed 104 may provide for or facilitate the operatingpressures in the reactor 106. Moreover, in one implementation, thesystem 200 may include upstream equipment (e.g., desulfurizer,pre-reformer, etc.) to process or treat the feed 104.

The CH₄ content (or natural gas content) in the feed 104 may be at avolume concentration, for example, in the ranges of 20% to 60%, 25% to60%, or 25% to 50%, or less than 60 vol %, less than 50 vol %, or lessthan 30 vol %. The CO₂ content in the feed 104 may be at a volumeconcentration in the ranges of 40% to 80%, 40% to 75%, or 50% to 75%, orat least 40 vol %, at least 50 vol %, or at least 75 vol %.

In certain embodiments, the dry reforming in the dry reformer 208 is afixed-bed catalytic process. Thus, the dry reformer 208 may have a fixedbed of dry reformer catalyst (dry reforming catalyst). The dry reformingin the dry reformer 208 may be a catalytic reaction where, for instance,the catalyst has an oxide support with active metal or metal sitesavailable for the reaction. The dry reformer catalyst may be, forexample, a nickel-based catalyst. The dry reformer catalyst may be orinclude, for example, noble metals, nickel (Ni), or Ni alloys. In someembodiments, the catalyst is magnesium oxide (MgO) or MgO nanoparticles.The MgO or MgO nanoparticles may be promoted with Ni and/or molybdenum(Mo), for example. In one implementation, the catalyst is MgOnanoparticles promoted with Ni and Mo. Other dry reformer catalysts areapplicable.

Again, the feed 104 to the reactor 206 and thus to the dry reformer 208includes CH₄ and CO₂. While O₂ is generally not fed to the dry reformer208, 02 may be involved in the dry reforming via the dissociation of theCO₂. With respect to the dry reforming mechanism, the dry reforming maydisassociate CO₂ into O₂ and CO. A re-oxidation reaction may occur viathe O₂ at reduced oxide sites of the catalyst support in someimplementations. The oxygen from the oxide site of the catalyst supportcan react with CH₄ to produce CO and H₂ as contribution to the syngas.

The dry reforming reaction is typically endothermic. Thus, in operation,heat is added to the dry reformer 208. In some implementations, theportion of the reactor 206 vessel having the dry reformer 208 may have avessel jacket for flow of heat transfer fluid (e.g., steam, hot oil, hotsynthetic fluid, etc.) to transfer heat from the heat transfer fluidfrom the jacket through the vessel wall to the dry reforming reactionmixture in the dry reformer 208. In addition or in lieu of a vesseljacket, electrical heaters may provide heat for the endothermic dryreforming reaction. The electrical heaters may be disposed in thereactor 206 vessel in the dry reformer 208 or on an external surface ofreactor 206 vessel at the dry reformer 208. Other configurations of heattransfer and temperature control of the dry reformer 208 are applicable.The operating temperature in the dry reformer 208 may be, for example,at less than 850° C., less than 800° C., in the range of 700° C. to 900°C., in the range of 750° C. to 875° C., or in the range of 800° C. to850° C. The operating pressure of (in) the dry reformer 208 may be, forexample, in the range of 10 bars to 70 bars.

As discussed, hydrogen may be added to the reactor 206 to increase themolar ratio of H₂ to CO of the syngas generated by the dry reformer 208.Hydrogen may be added to the reactor 206 vessel at an inlet nozzle ofthe reactor vessel into an internal discharge portion of the dryreformer 208 or at other parts of the reactor 206. The source of the H₂may be, for example, a H₂ piping header or a H₂ tube trailer, and thelike. In some implementations, the source of the H₂ is a waterelectrolysis unit. The H₂ supplied by the water electrolysis unit may belabeled as renewable H₂ in implementations in which the waterelectrolysis unit is driven by renewable energy sources, such as energysources relying on wind or solar.

The syngas (including any added H₂) is cooled in the heat exchanger 210.The heat exchanger 210 is generally disposed within the reactor 206vessel. In operation, the heat exchanger 210 cools (removes heat from)the syngas discharged from the dry reformer 208 The cooling medium forthe heat exchanger 210 may be, for example, cooling water. The coolingmedium may flow through the heat exchanger 210 to absorb heat from thesyngas. The heat exchanger 210 may be, for example, a shell-and-tubeheat-exchanger type or configuration in which the tubes are situated inthe reactor 206 vessel. The reactor 206 vessel wall may act as the shellof the heat exchanger 210 housing the tubes, or the shell of the heatexchanger 210 housing the tubes is disposed in the reactor 206 vessel.Other heat exchanger configurations are applicable.

The methanol synthesis reactor 212 in the reactor 206 vessel receivesthe cooled syngas that flows from (discharged from) the heat exchanger210. The methanol synthesis reaction in the methanol synthesis reactor212 that converts the syngas to methanol 102 is generally exothermic.Therefore, the reactor 206 vessel at the methanol synthesis reactor 212may have a vessel jacket for a heat-transfer fluid that is a coolingmedium (e.g., cooling water). In addition to (or in lieu of) a vesseljacket, the reactor 206 vessel may have cooling coils internally in themethanol synthesis reactor 212 that route a cooling medium. Theoperating temperature in the methanol synthesis reactor 212 may be, forexample in the range of 175° C. to 325° C., or in a range of 200° C. to300° C., or at least 175° C., at least 200° C., or less than 350° C. Theoperating pressure may be, for example, in a range of 10 bars to 70 barsor in a range of 10 bars to 50 bars.

The methanol synthesis reactor 212 has methanol synthesis catalyst toconvert the syngas to methanol (e.g., methanol 102). The methanolsynthesis catalyst may be, for example, a Cu-based catalyst, CuO-basedcatalyst CuO—ZnO based catalyst, etc. The methanol 102 generated via themethanol synthesis discharges in the reactor 206 effluent 110 from themethanol synthesis reactor 212 and thus from the reactor 206 vessel inthe illustrated implementation.

The system 200 may include a separation system 214 that may be analogousto the downstream system 108 of FIG. 1 . In FIG. 2 , the effluent 110may be processed in the separation system 214 to give the methanol 102product. Components (e.g., H₂, CO, CO₂, etc.) may be removed from theeffluent 110 to give the product methanol 102. These removed componentsmay be recycled to the reactor 206. In the illustrated embodiment, tworecycle streams 216, 218 having at least some of these removedcomponents are depicted. The recycle stream 216 is fed to the dryreformer 208. The recycle stream 218 is fed to the methanol synthesisreactor 212. In implementations, the recycle streams 216, 218 may eachbe primarily the combination of H₂, CO, and CO₂. The recycle stream 216and the recycle stream 218 may have the same composition. On the otherhand, the recycle stream 216 may have a composition different from thecomposition of the recycle stream 218. For instance, the concentrationof CO₂ in the recycle stream 216 may be greater than the concentrationof CO₂ than the recycle stream 218.

The separation system 214 may employ, for example, a multi-stage coolingseparation. The separation system 214 may be or include a multi-stagecooling separation unit. The multi-stage cooling may includecondensation and flash separation. The gas phase flow of a flashseparation vessel after cooling and partial condensation may enter thenext flash separation vessel. The separation system(s) may include amembrane separator vessel, a distillation column, a vessel havingadsorbent, and so forth. In the illustrated embodiment, the productmethanol 102 stream discharges from separation system 214.

The system 200 may include the control system 148, as discussed withrespect to FIG. 1 . The control system 146 may direct or facilitateoperations of the system 200.

FIG. 3 is a method 300 of producing methanol via dry reforming andmethanol synthesis in the same vessel. The vessel may be a vessel of areactor. Thus, the vessel may be a reactor vessel.

Therefore, a reactor having a reactor vessel may perform both the dryreforming and methanol synthesis in the same reactor vessel.Accordingly, the reactor may perform two different types of reaction(dry reforming and methanol synthesis) in the same reactor vessel.

At block 302, the method includes providing feed including methane andcarbon dioxide to the vessel. The method may provide the feed to a dryreformer (or dry reforming section) in the vessel. Again, the vessel maybe a vessel of a reactor and thus be labeled as the reactor vessel. Thevessel may have a feed inlet (e.g., inlet nozzle) to receive the feed.The feed inlet nozzle may be coupled (e.g., flanged connection, threadedconnection, etc.) to a supply conduit conveying the feed to the vessel.The vessel may include more than one feed inlet nozzles to receive thefeed. In certain implementations, a control valve is disposed along aconduit conveying the carbon dioxide for the feed. The control valvecontrols flow rate of the carbon dioxide to give a specified amount ofcarbon dioxide of the feed. Thus, the method may include controlling theflow rate of the carbon dioxide provided for the feed to the vessel togive a specified amount of carbon dioxide of the feed. The specifiedamount of carbon dioxide of the feed may be, for example, ratio (e.g.,molar ratio) of the carbon dioxide to the methane of the feed or aconcentration (e.g., vol % or mol %) of the carbon dioxide in the feed.

At block 304, the method includes converting the methane and the carbondioxide by dry reforming (e.g., via dry reforming catalyst) in thevessel into syngas including hydrogen and carbon monoxide. The dryreforming may be performed via the dry reforming catalyst in a dryreformer (or dry reforming section) in the vessel. The dry reformingcatalyst may be a fixed bed of catalyst in the dry reforming section(dry reformer) in the vessel.

At block 306, the method may include adding hydrogen to the vessel, suchas to increase the ratio (e.g., molar ratio) in the syngas of hydrogento carbon monoxide. The vessel may have a hydrogen inlet (e.g., inletnozzle) coupled to a hydrogen supply conduit (external to the vessel) toreceive the hydrogen to increase the molar ratio of hydrogen to carbonmonoxide of the syngas in the vessel. In some implementations, a waterelectrolysis unit (including a water-electrolysis electrochemical cell)provides the hydrogen through the hydrogen supply conduit to thehydrogen inlet on the vessel. In certain implementations, a flow controlvalve is disposed along the supply conduit conveying the hydrogen to thehydrogen inlet on the vessel, wherein the control valve controls flowrate of the hydrogen from the hydrogen source (e.g., water electrolysisunit) to the vessel.

At block 308, the method includes cooling the syngas via a heatexchanger (heat exchange section) in the vessel. The method may includeflowing the syngas from the dry reforming section through the heatexchange section in the vessel to cool the syngas with a cooling medium(e.g., cooling water) in the heat exchange section. The heat exchangesection may include the heat exchanger that cools the syngas with thecooling medium, and wherein flowing the syngas from the dry reformingsection through the heat exchange section includes flowing the syngasthrough the heat exchanger (e.g., shell-and-tube heat exchanger).

At block 310, the method includes synthesizing methanol (e.g., viamethanol synthesis catalyst) from the syngas in the vessel. The methodmay include flowing the syngas as cooled from the heat exchange section(heat exchanger) to the methanol synthesis section in the vessel, andsynthesizing methanol from the syngas via the methanol synthesiscatalyst in the methanol synthesis section. The methanol synthesiscatalyst may be a fixed bed of catalyst in the methanol synthesissection (methanol synthesis reactor) in the vessel to give the methanolas a component of the vessel effluent.

At block 312, the method includes discharging effluent (having themethanol) from the vessel. The vessel may have an outlet dischargenozzle to discharge the effluent from the vessel into an effluentdischarge conduit. The discharging of the effluent from the vessel maybe discharging the effluent from the methanol synthesis section (ormethanol synthesis reactor) in the vessel. Again, the vessel may have aneffluent outlet (outlet nozzle) coupled to an effluent discharge conduitexternal to the vessel for discharge of the effluent from the vessel(e.g., to a separation system, as discussed with respect to block 314).

At block 314, the method may include processing the effluent (asdischarged) to remove components (e.g., H₂, CO, CO₂, H₂O, any unreactedmethane, etc.) from the effluent to give the methanol as product. Inimplementations, the combination of hydrogen, carbon monoxide, andcarbon dioxide may be the majority of the components removed. Theprocessing of the effluent to remove the components may be performed ina separation system (e.g., including at least one flash vessel). Inimplementations, the separation system may be a multi-stage cooling(including partial condensation) system. Other unit operations for theseparation system may be implemented, such as membrane separation(membrane separator vessel), distillation (distillation column), and soon.

At block 316, the method may include providing (recycling, returning) atleast one of the components removed from the effluent to the vessel. Thevessel may include an inlet (e.g., an inlet nozzle) to receive at leastone of the components removed from the effluent. The inlet nozzle may becoupled to a conduit conveying the component(s) from the separationsystem. The method may include providing (e.g., via a conduit) at leastone of the hydrogen, the carbon monoxide, or the carbon dioxide removedfrom the effluent to the dry reforming section (dry reformer) in thevessel. The vessel may have an inlet nozzle at the dry reforming sectionto receive this return of component(s) to the vessel. The method mayinclude providing (e.g., via a conduit) at least one of the hydrogen,the carbon monoxide, or the carbon dioxide removed from the effluent tothe methanol synthesis section. The vessel have an inlet nozzle at themethanol synthesis section to receive this return of component(s) to thevessel. An embodiment a method of producing methanol via dry reformingand methanol synthesis, the method including providing feed includingmethane and carbon dioxide to a vessel, converting methane and carbondioxide in the vessel into syngas including hydrogen and carbon monoxidevia dry reforming in the vessel, cooling the syngas via a heat exchangerin the vessel, synthesizing methanol from the syngas in the vessel, anddischarging effluent (including methanol) from the vessel. The methodmay include heating a dry reforming section of the vessel and cooling amethanol synthesis section of the vessel. The method may includeprocessing the effluent as discharged to remove components from theeffluent to give the methanol as product, the components includinghydrogen, carbon monoxide, and carbon dioxide. If so, the method mayinclude recycling the hydrogen, the carbon monoxide, and the carbondioxide removed from the effluent to the vessel. The converting of themethane and the carbon dioxide in the vessel may involve converting themethane and the carbon dioxide via dry reforming catalyst in the vesselinto the syngas. The synthesizing of the methanol may involvesynthesizing the methanol from the syngas via methanol synthesiscatalyst in the vessel. The method may include adding hydrogen to thevessel to increase a molar ratio of hydrogen to carbon monoxide of thesyngas.

Another embodiment is a method of producing methanol, includingconverting (dry reforming) methane and carbon dioxide via a dryreforming catalyst in a dry reforming section in a reactor vessel intosyngas including hydrogen and carbon monoxide, wherein the convertingincludes dry reforming. The method may include providing feed includingthe methane and the carbon dioxide to the dry reforming section in thereactor vessel. The method includes flowing the syngas from the dryreforming section through a heat exchange section in the reactor vesselto cool the syngas with a cooling medium in the heat exchange section.The heat exchange section may have a heat exchanger that cools thesyngas with the cooling medium, wherein flowing the syngas from the dryreforming section through the heat exchange section includes flowing thesyngas through the heat exchanger. The method includes flowing thesyngas as cooled from the heat exchange section to a methanol synthesissection in the reactor vessel. The method includes synthesizing methanolfrom the syngas via a methanol synthesis catalyst in the methanolsynthesis section. The method may include discharging effluent includingthe methanol from the reactor vessel. The method may include processingeffluent including the methanol discharged from the reactor vessel toremove hydrogen, carbon monoxide, and carbon dioxide from the effluentto give the methanol as product. If so, the method may include providingat least one of the hydrogen, the carbon monoxide, or the carbon dioxideremoved from the effluent to the dry reforming section. The method mayinclude providing at least one of the hydrogen, the carbon monoxide, orthe carbon dioxide removed from the effluent to the methanol synthesissection.

Yet another aspect relates to a methanol production system including areactor vessel having a feed inlet to receive a feed including methaneand carbon dioxide. A control valve may be disposed along a conduitconveying the carbon dioxide for the feed to control flow rate of thecarbon dioxide to give a specified amount of carbon dioxide of the feed.The specified amount may be a ratio of the carbon dioxide to the methaneof the feed or a concentration of the carbon dioxide in the feed. Thereactor vessel includes a dry reforming section having a dry reformingcatalyst in the reactor vessel to convert the methane and the carbondioxide into syngas including hydrogen and carbon monoxide. The dryreforming catalyst may be a fixed bed of catalyst in the dry reformingsection in the reactor vessel. The reactor vessel includes a heatexchange section having a heat exchanger in the reactor vessel toreceive the syngas from the dry reforming section and cool the syngaswith a cooling medium. The heat exchanger may be a shell-and-tube heatexchanger. The cooling medium may include cooling water. The reactorvessel includes a methanol synthesis section having a methanol synthesiscatalyst in the reactor vessel to synthesize methanol from the syngasand discharge an effluent including the methanol from the reactorvessel. The methanol synthesis catalyst may be a fixed bed of catalystin the methanol synthesis section in the reactor vessel. The methanolproduction system may include a separation system to remove componentsfrom the effluent as discharged to give the methanol as methanolproduct, the components removed including hydrogen, carbon monoxide, andcarbon dioxide, wherein the separation system includes a flash vessel,and wherein the reactor vessel has an effluent outlet for discharge ofthe effluent from the reactor vessel. The reactor vessel may have aninlet to receive at least one of the components removed from theeffluent. The reactor vessel may have a hydrogen inlet to receivehydrogen to increase a molar ratio of hydrogen to carbon monoxide of thesyngas in the reactor vessel. A water electrolysis unit including awater-electrolysis electrochemical cell may provide the hydrogenreceived at the hydrogen inlet. A control valve disposed along a conduitconveying the hydrogen to the hydrogen inlet, wherein the control valvecontrols flow rate of the hydrogen from the water electrolysis unit tothe reactor vessel.

EXAMPLES

The Examples are given only as examples and not meant to limit thepresent techniques. Examples 1-4 are presented.

Examples 1 and 2

Conditions of Examples 1 and 2 are given in Table 1. In Example 1, thefeed (excluding nitrogen) was 50 mol % CO₂ and 50 mol % CH₄. In Example2, the feed (excluding nitrogen) was 75 mol % CO₂ and 25 mol % CH₄.Nitrogen gas was fed along with the CH₄ and CO₂. Nitrogen is inert anddoes not react.

In Example 1, an evaluation of a dry reforming catalyst was performed inthe laboratory with micro-reactor and online gas chromatography (GC).The micro-reactor was a stainless-steel tube with diameter of 9millimeters (mm) mounted in a furnace. During the micro-scale testing,about 1 gram of catalyst was added to the tube, and the tube mounted inthe furnace. Methane, carbon dioxide, and nitrogen were introduced tothe furnace by a mass flow controller. The temperature of reactor wasincreased up to 800° C. with a ramp of 10° C./minute and kept at 800° C.during the reaction. Composition of effluent gas discharged from thereactor was analyzed from online GC in order to calculate conversionsand H₂/CO molar ratio. The time on stream for the reaction was 850hours. The conversion of CH₄ and the conversion of CO₂ were both about100% over the entire 850 hours.

In Example 2, an evaluation of the dry reforming catalyst (same catalystas in Example 1) was performed in the laboratory with micro-reactor andonline gas chromatography (GC). The micro-reactor was a stainless-steeltube with diameter of 9 millimeters (mm) mounted in a furnace. Duringthe micro-scale testing, about 1 gram of catalyst was added to the tube,and the tube mounted in the furnace. Methane, carbon dioxide, andnitrogen were introduced to the furnace by a mass flow controller. Thetemperature of reactor was increased up to 800° C. with a ramp of 10°C./minute and kept at 800° C. during the reaction. Composition ofeffluent gas discharged from the reactor was analyzed from online GC inorder to calculate conversions and H₂/CO molar ratio. The time on streamfor the reaction was 24 hours. The conversion of CH₄ over the 24 hourswas consistently about 95%. The conversion of CO₂ over the 24 hours wasconsistently about 45%.

TABLE 1 Evaluation of dry reforming catalyst - Example 1 and Example 2Example 1 Example 2 Catalyst Nickel-based catalyst Nickel-based catalystCO2 Feed 50% 75% CH4 Feed 50% 25% Temperature 800° C. 800° C. Pressure 1bar 14 bars Conversions CH4:100%, CO2:100% CH4: ~95%, CO2: ~45% H2/COmolar ratio ~1 ~0.5 Time on stream (hours) 850 24

Examples 3 and 4

A reactor was simulated via Aspen Plus® software (version 10). AspenPlus® software is available from Aspen Technology, Inc. havingheadquarters in Bedford, Mass., USA. The reactor simulated has a dryreforming part and methanol synthesis part (and heat exchanger disposedthere between), such as the reactor 106, 206 discussed above withrespect to FIGS. 1-2 .

FIG. 4 is the Aspen simulation diagram for the two simulations performedin Example 3 and Example 4, respectively. The stream temperaturesdepicted in FIG. 4 are in ° C. The stream information for the streamlabels in FIG. 4 is in Table 4 (Example 3) and Table 7 (Example 4)below. In the simulations, the Aspen stoichiometric reactor was utilizedfor simulating the dry reforming part (the dry reformer in the vessel)and the methanol synthesis part (the methanol synthesis reactor in thevessel), respectively. The Aspen heat exchanger was applied to mimic theheat exchanger in the vessel. For dry reforming conditions andconversions, the aforementioned catalyst experimental results (as seenin Table 1) were applied. Methanol synthesis conditions are typicalconditions. The values for methanol selectivity and CO conversion areinput.

Based on the simulation results for Example 3, it was found that 31.6kilogram per day (kg/day) of CO₂ and 11.55 kg/day of CH₄ and 5.81 kg/dayof extra H₂ enabled to ideally produce 46.14 kg/day of methanol. Basedon the simulation results for Example 4, 11.55 kg/day of CH₄, 95.06kg/day of CO₂ and 9.68 kg/day of extra H₂ can ideally produce 61.52kg/day of methanol.

TABLE 2 Dry Reforming Conditions for Example 3 Dry reforming conditions1 Feed 50 mol % CH4, 50 mol % CO2 Catalyst Ni-based catalyst Temperature850 °C Pressure 40 bars Conversion 100% CH4, 100% CO2 Products H2:CO =1:1

TABLE 3 Methanol Synthesis Conditions for Example 3 Methanol synthesisconditions Feed H2:CO = 3:1 molar ratio Catalyst Cu-based catalystTemperature 250° C. Pressure 50 bars Conversion 99% CO Products 99 mol %methanol will be collected

TABLE 4 Stream Information for Example 3 Stream CH4 CO2 1ST-PROD H2AFT-MXR AFT-HEX FIN-PROD Phase Vapor Vapor Vapor Vapor Vapor Vapor VaporTemp (° C.) 25 25 850 25 451.66 250 250 Press (bar) 50 50 50 50 50 50 50Mole Fractions (mol%) CH4 100%   0%  0%   0%  0%  0%  0% CO2   0% 100% 0%   0%  0%  0%  0% H2O   0%   0%  0%   0%  0%  0%  0% H2   0%   0% 50%100% 75% 75% 50% CO   0%   0% 50%   0% 25% 25%  0% METHANOL   0%   0% 0%   0%  0%  0% 50% Mass Flows (kg/day) CH4 11.55 0.00 0.00 0.00 0.000.00 0.00 CO2 0.00 31.69 0.00 0.00 0.00 0.00 0.00 H2O 0.00 0.00 0.000.00 0.00 0.00 0.00 H2 0.00 0.00 2.90 5.81 8.71 8.71 2.90 CO 0.00 0.0040.33 0.00 40.33 40.33 0.00 METHANOL 0.00 0.00 0.00 0.00 0.00 0.00 46.14

TABLE 5 Dry Reforming Conditions for Example 4 Dry reforming conditions2 Feed 25 mol % CH4, 75 mol % CO2 Catalyst Ni based catalyst Temperature850° C. Pressure 40 bars Conversion 100% CH4, 55% CO2 Products H2:CO =1:2 molar ratio

TABLE 6 Methanol Synthesis Conditions for Example 4 Methanol synthesisconditions Feed H2:CO = 3:1 molar ratio Catalyst Cu-based catalystTemperature 250° C. Pressure 50 bars Conversion 99% CO Products 99 mol %methanol may be collected

TABLE 7 Stream Information for Example 4 Stream CH4 CO2 1ST-PROD H2AFT-MXR AFT-HEX FIN-PROD Phase Vapor Vapor Vapor Vapor Vapor Vapor VaporTemp (C) 25 25 850 25 466.95 250 250 Press (bar) 50 50 50 50 50 50 50Mole Fractions (mol%) CH4 100%   0%  0%   0%  0%  0%  0% CO2   0% 100%22%   0% 11% 11% 18% H2O   0%   0% 11%   0%  5%  5%  9% H2   0%   0% 22%100% 63% 63% 36% CO   0%   0% 44%   0% 21% 21%  0% METHANOL   0%   0% 0%   0%  0%  0% 36% Mass Flows (kg/day) CH4 11.55 0.00 0.00 0.00 0.000.00 0.00 CO2 0.00 95.06 42.25 0.00 42.25 42.25 42.25 H2O 0.00 0.00 8.650.00 8.65 8.65 8.65 H2 0.00 0.00 1.94 9.68 11.61 11.61 3.87 CO 0.00 0.0053.78 0.00 53.78 53.78 0.00 METHANOL 0.00 0.00 0.00 0.00 0.00 0.00 61.52

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure.

What is claimed is:
 1. A method of producing methanol via dry reformingand methanol synthesis, the method comprising: providing feed comprisingmethane and carbon dioxide to a dry reforming section in a vessel, thevessel comprising a vessel wall, wherein the dry reforming section and amethanol synthesis section are enclosed within the vessel in an interiorof the vessel to inside of the vessel wall; converting methane andcarbon dioxide in the vessel into syngas comprising a molar ratio ofhydrogen (H₂) and carbon monoxide by dry reforming via dry reformingcatalyst in the dry reforming section in the vessel; injecting H₂ intothe syngas in the reactor vessel in response to specifying to increase amolar ratio of H₂ to carbon monoxide of the syngas in the reactorvessel, wherein the H₂ injected is injected into a discharge portion ofthe dry reforming section or into a heat exchanger in the vessel thatreceives the syngas from the dry reforming section; cooling the syngasvia the heat exchanger in the vessel, wherein the heat exchanger isdisposed between the dry reforming section and the methanol synthesissection; synthesizing methanol from the syngas discharged from the heatexchanger via methanol synthesis catalyst in the methanol synthesissection in the vessel; discharging effluent from the vessel, theeffluent comprising the methanol; processing the effluent as dischargedto remove components from the effluent to give the methanol as product,the components comprising H₂, carbon monoxide, and carbon dioxide; andrecycling carbon dioxide removed from the effluent to the dry reformingsection.
 2. The method of claim 1, comprising: combining a carbondioxide stream and a methane stream to give the feed, wherein the carbondioxide stream comprises at least 90 volume percent (vol %) of carbondioxide; and heating the dry reforming section of the vessel and coolingthe methanol synthesis section of the vessel.
 3. The method of claim 2,wherein the methane stream comprises a methane-rich stream comprisingnatural gas having at least 60 vol % of methane, and wherein a source ofthe H₂ injected into the syngas comprises a water electrolysis unitcomprising a water-electrolysis electrochemical cell.
 4. The method ofclaim 2, comprising: controlling flow rate of the carbon dioxide streamor flow rate of the methane stream, or both, to give a specified vol %of carbon dioxide in the feed in the range of 30 vol % to 70 vol % or aspecified molar ratio of carbon dioxide to methane in the feed in arange of 1 to 3, and recycling carbon monoxide removed from the effluentto the vessel.
 5. The method of claim 1, wherein a molar ratio of thecarbon dioxide to the methane in the feed is in a range of 1 to 3,wherein the syngas upstream of receiving the H₂ as injected comprises amolar ratio of H₂ to carbon monoxide in a range of 0.4 to 1, wherein theH₂ injected is not injected into the methanol synthesis section, andwherein steam is not introduced to the vessel.
 6. The method of claim 2,comprising measuring composition of the effluent and in response to thecomposition as measured, adjusting at least one of flow rate of thecarbon dioxide stream or flow rate of the H₂ injected into the syngas inthe vessel, wherein injecting the H₂ into the syngas in the vesselincreases the molar ratio of H₂ to carbon monoxide of the syngas to in arange of 1 to
 3. 7. A method of producing methanol, comprising:converting methane and carbon dioxide via a dry reforming catalyst in adry reforming section in a reactor vessel into syngas comprisinghydrogen (H₂) and carbon monoxide, wherein the converting comprises dryreforming; flowing the syngas from the dry reforming section through aheat exchange section in the reactor vessel to cool the syngas with acooling medium in the heat exchange section; injecting H₂ into thesyngas in the reactor vessel in response to specifying to increase amolar ratio of H₂ to carbon monoxide of the syngas in the reactorvessel, wherein the H₂ injected is injected into a discharge portion ofthe dry reforming section or into the heat exchange section; flowing thesyngas as cooled from the heat exchange section to a methanol synthesissection in the reactor vessel, wherein the dry reforming section and themethanol synthesis section are enclosed within the reactor vessel in aninterior of the reactor vessel; synthesizing methanol from the syngasvia a methanol synthesis catalyst in the methanol synthesis section;discharging effluent comprising the methanol from the reactor vessel;processing the effluent to remove hydrogen, carbon monoxide, and carbondioxide from the effluent to give the methanol as product; and providingcarbon dioxide removed from the effluent to the dry reforming section.8. The method of claim 7, comprising: providing feed comprising themethane and the carbon dioxide to the dry reforming section in thereactor vessel; and combining a carbon dioxide stream and a methanestream to give the feed, wherein the carbon dioxide stream comprises atleast 90 volume percent (vol %) of carbon dioxide and the methane streamcomprises at least 60 vol % of methane.
 9. The method of claim 8,wherein an amount of the carbon dioxide in the feed is at least 40 vol%, wherein the syngas upstream of receiving the H₂ as injected comprisesa molar ratio of H₂ to carbon monoxide in a range of 0.4 to 1, whereinthe H₂ injected is not injected into the methanol synthesis section, andwherein the heat exchange section comprises a heat exchanger that coolsthe syngas with the cooling medium, and wherein flowing the syngas fromthe dry reforming section through the heat exchange section comprisesflowing the syngas through the heat exchanger.
 10. The method of claim8, comprising controlling flow rate of the carbon dioxide stream via acontrol valve to give a specified vol % of carbon dioxide in the feed ofat least 40 vol % or a specified molar ratio of carbon dioxide tomethane in the feed in a range of 1 to
 3. 11. The method of claim 8,comprising: measuring composition of the effluent and in response to thecomposition as measured, adjusting at least one of flow rate of thecarbon dioxide stream or flow rate of the H₂ injected into the syngas inthe reactor vessel; and providing hydrogen and carbon monoxide removedfrom the effluent to the reactor vessel.
 12. The method of claim 7,wherein a water electrolysis unit comprising a water-electrolysiselectrochemical cell provides the H₂ injected into the syngas in thereactor vessel, and wherein injecting the H₂ into the syngas in thereactor vessel increases a molar ratio of H₂ to carbon monoxide of thesyngas to in a range of 1 to
 3. 13. The method of claim 1, comprising:determining composition of the syngas, wherein the syngas upstream ofreceiving the H₂ as injected comprises a molar ratio of H₂ to carbonmonoxide in a range of 0.4 to 1, and wherein the molar ratio asspecified is in a range of 1 to 3; and adjusting flow rate of the H₂injected via a control valve in response to the composition asdetermined and to give the molar ratio as specified, wherein the controlvalve is disposed along a conduit conveying the H₂ to the vessel, andwherein the H₂ injected is not injected into the methanol synthesissection.
 14. The method of claim 7, comprising: determining compositionof the syngas, wherein the syngas upstream of receiving the H₂ asinjected comprises a molar ratio of H₂ to carbon monoxide in a range of0.4 to 1, wherein the molar ratio as specified is in a range of 1 to 3;and adjusting flow rate of the H₂ injected via a control valve inresponse to the composition as determined and to give the molar ratio asspecified, wherein the control valve is disposed along a conduitconveying the H₂ to the reactor vessel, and wherein the H₂ injected isnot injected into the methanol synthesis section.